1/*!
2@file
3Defines `boost::hana::hash`.
4
5Copyright Jason Rice 2016
6Distributed under the Boost Software License, Version 1.0.
7(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
8 */
9
10#ifndef BOOST_HANA_HASH_HPP
11#define BOOST_HANA_HASH_HPP
12
13#include <boost/hana/fwd/hash.hpp>
14
15#include <boost/hana/concept/hashable.hpp>
16#include <boost/hana/concept/integral_constant.hpp>
17#include <boost/hana/config.hpp>
18#include <boost/hana/core/dispatch.hpp>
19#include <boost/hana/fwd/integral_constant.hpp>
20#include <boost/hana/type.hpp>
21
22#include <type_traits>
23
24
25namespace boost { namespace hana {
26 //! @cond
27 template <typename X>
28 constexpr auto hash_t::operator()(X const& x) const {
29 using Tag = typename hana::tag_of<X>::type;
30 using Hash = BOOST_HANA_DISPATCH_IF(hash_impl<Tag>,
31 hana::Hashable<Tag>::value
32 );
33
34#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
35 static_assert(hana::Hashable<Tag>::value,
36 "hana::hash(x) requires 'x' to be Hashable");
37#endif
38
39 return Hash::apply(x);
40 }
41 //! @endcond
42
43 template <typename Tag, bool condition>
44 struct hash_impl<Tag, when<condition>> : default_ {
45 template <typename X>
46 static constexpr auto apply(X const&) = delete;
47 };
48
49 namespace detail {
50 template <typename T, typename = void>
51 struct hash_integral_helper;
52
53 template <typename Member, typename T>
54 struct hash_integral_helper<Member T::*> {
55 template <typename X>
56 static constexpr auto apply(X const&) {
57 return hana::type_c<hana::integral_constant<Member T::*, X::value>>;
58 }
59 };
60
61 template <typename T>
62 struct hash_integral_helper<T,
63 typename std::enable_if<std::is_signed<T>::value>::type
64 > {
65 template <typename X>
66 static constexpr auto apply(X const&) {
67 constexpr signed long long x = X::value;
68 return hana::type_c<hana::integral_constant<signed long long, x>>;
69 }
70 };
71
72 template <typename T>
73 struct hash_integral_helper<T,
74 typename std::enable_if<std::is_unsigned<T>::value>::type
75 > {
76 template <typename X>
77 static constexpr auto apply(X const&) {
78 constexpr unsigned long long x = X::value;
79 return hana::type_c<hana::integral_constant<unsigned long long, x>>;
80 }
81 };
82
83 template <>
84 struct hash_integral_helper<bool> {
85 template <typename X>
86 static constexpr auto apply(X const&) {
87 return hana::type_c<hana::integral_constant<bool, X::value>>;
88 }
89 };
90
91 template <>
92 struct hash_integral_helper<char> {
93 template <typename X>
94 static constexpr auto apply(X const&) {
95 using T = std::conditional<std::is_signed<char>::value,
96 signed long long, unsigned long long
97 >::type;
98 constexpr T x = X::value;
99 return hana::type_c<hana::integral_constant<T, x>>;
100 }
101 };
102 }
103
104 template <typename Tag>
105 struct hash_impl<Tag, when<hana::IntegralConstant<Tag>::value>> {
106 template <typename X>
107 static constexpr auto apply(X const& x) {
108 using T = typename std::remove_cv<decltype(X::value)>::type;
109 return detail::hash_integral_helper<T>::apply(x);
110 }
111 };
112}} // end namespace boost::hana
113
114#endif // !BOOST_HANA_HASH_HPP
115

source code of boost/libs/hana/include/boost/hana/hash.hpp